pinctrl: sh-pfc: r8a7792: Add VIN pin groups

Add VIN[0-5] pin groups to the R8A7792 PFC driver.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
[geert: Fix VI1_D14_G6_Y6 and VI1_D15_G7_Y7 pins]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>